SPECIFICATIONS FOR EXCAVATION FOR ROAD


 

SPECIFICATIONS

The details of different items of work, the quantity of materials, proportion of mortar and workman ship which are described in specifications.

Specifications are of two types:

·         General or Brief specifications

·         Detail specifications

 

General or Brief specification: 

It is a short description of different parts of the work specifying materials, proportions, qualities etc.

 

Detailed Specification:

The detail specifications of different items of work are prepared separately, and describe what the work should be and how they shall be executed and constructed.

The detail specifications form an important part of contract document.

GENERAL/ BREIF SPECIFICATION FOR EXCAVATION FOR ROAD WORKS

Excavation shall be done for removal of all materials necessary for the construction of roadway in accordance with the requirements of specifications in the drawings or as directed by the Engineer-in-charge.

 

DETAILED SPECIFICATION FOR EXCAVATION FOR ROAD WORKS

 

SCOPE

This work shall consist of excavation, removal and satisfactory disposal of all materials necessary for the construction of roadway in accordance with requirements of these specifications and the lines, grades and cross-sections shown in the drawings or as directed by the Engineer-in-charge. It shall include the hauling and stacking of or hauling to sites of embankment and sub grade construction, suitable cut materials in specified manner, trimming and finishing of the road to specified dimensions or as directed by the Engineer-in-charge.

 

Construction operations

Setting out:  After the site has been cleared the limits of excavation shall be set out true to lines, curves, slopes, grades, and sections, as shown on the drawings or as directed by the Engineer-in-charge. The contractor shall provide all labour, survey instruments and materials such as strings, pegs, nails, bamboos, stones, lime, mortar, concrete, etc., required in connection with the setting out of works and the establishment of bench marks. The contractor shall be responsible for the maintenance of bench marks and other marks and stakes as long as in the opinion of the Engineer-in-charge, they are required for the work.

 

 

Excavation – General: All excavations shall be carried out in conformity with the directions laid here in under and in a manner approved by the Engineer-in-charge. The work shall be do done that the suitable materials available from excavation are satisfactorily utilized as decided upon beforehand.

            The excavations shall conform to the lines, grades, side slopes and levels shown on the drawings or as directed by the Engineer-in-charge. The contractor shall not excavate outside the limits of excavation. Subject to the permitted tolerances, any excess depth/ width excavated beyond the specified levels/ dimensions on the drawings shall be made good at the cost of the contractor with suitable material of characteristics similar to that removed and compacted to the requirements.

All debris and loose material on the slopes of cuttings shall be removed. No backfilling shall be allowed to obtain required slopes excepting that when boulders or soft materials are encountered in cut slopes, these shall be excavated to approved depth on instructions of the Engineer-in-charge and the resulting cavities filled with suitable material and thoroughly compacted in an approved manner. After excavation, the sides of excavated area shall be trimmed and the area contoured to minimize erosion and ponding, allowing for natural drainage to take place.

Methods, tools and equipment: Only such methods, tools and equipment as approved by the Engineer-in-charge shall be adopted in the work. If so desired by the Engineer-in-charge, the contractor shall demonstrate the efficiency of the type of equipment to be used before the commencement of work.    

Rock excavation: Rock, when encountered in road excavation, shall be removed up to the formation level or as otherwise indicated on the drawings. Where, however, unstable shales or other unsuitable materials are encountered at the formation level, these shall be excavated to the extent of 500 mm below the formation level or as otherwise specified. In all cases, the excavation operations shall be so carried out that at no point on cut formation the rock protrudes above the specified levels. Rocks and large boulders which are likely to cause

 

differential settlements and also local drainage problems should be removed to the extent of 500 mm below the  formation level in full formation width including drains and cut through the side drains. Slopes in rock cutting shall be finished to uniform lines corresponding to slope lines shown on the drawings or as directed by the Engineer-in-charge. Notwithstanding the foregoing, all loose pieces of rock on excavated slope surface which move when pierced by a crowbar shall be removed.

Marsh excavation: The excavation of soils from marshes/swamps shall be carried out as per the programme approved by the Engineer-in-charge.

           Excavation of marshes shall begin at one end and proceed in one direction across the entire marsh immediately ahead of backfilling. The method and sequence of excavating and backfilling shall be such as to ensure, to the extent practicable, the complete removal or displacement of all muck from within the lateral limits called for on the drawings or as stacked by the Engineer-in-charge, and to the bottom of the marsh, firm support or levels indicated.

Excavation of road shoulders/median for widening of pavement or providing treated shoulders: In works involving widening of existing pavements or providing treated shoulders, unless otherwise specified, the shoulder/median shall be removed to their full width and to levels shown on drawings or as indicated by the Engineer-in-charge. While doing so, care shall be taken to see that no portion of the existing pavement designated for retention is loosened or disturbed. If the existing pavement gets loosened or disturbed, it shall be dismantled and cut to a regular shape with sides vertical and the distributed/loosened portion removed completely and re-laid as directed by the Engineer-in-charge, at the cost of the contractor.

Slides: If slips, slides, over-breaks or subsidence occur in cuttings during the process of construction, they shall be removed at the cost of the contractor as ordered by the Engineer-in-charge. Adequate precautions shall be taken to ensure that during construction, the slopes are not rendered unstable or give rise to recurrent slides after construction. If finished slopes

 

slide into the road way subsequently, such slides shall be removed and paid for at the contract rate for the class of excavation involved, provided the slides are not due to any negligence on the part of the contractor. The classification of the debris material from the slips, slides etc. shall conform to its condition at the time of removal and payment made accordingly regardless of its condition earlier.

Dewatering: If water is met with in the excavations due to springs, seepage, rain or other causes, it shall be removed by suitable diversions, pumping or bailing out and the excavation kept dry whenever so required or directed by the Engineer-in-charge. Care shall be taken to discharge the drained water into suitable outlets as not to cause damage to the works, crops or any other property. Due to any negligence on the part of the contractor, if any such damage is caused, it shall be the sole responsibility of the contractor to repair/restore to the original condition at his own cost or compensate for the damage.

Disposal of excavated materials: All the excavated materials shall be the property of the employer. The material obtained from the excavation of the road way, shoulders shall be used for the filling up of

(i)     Road way embankment

(ii)   The existing pits in the right-of-way

(iii)  For landscaping of roads as directed by the Engineer-in-charge

Including leveling and spreading with all lifts and lead up to 1000 m and no extra payment shall be made for the same.

           All hard materials, such as hard moorum, rubble, etc., not intended use as above shall be stacked neatly on specified land as directed by the Engineer-in-charge with all lifts and lead up to 1000 m. Unsuitable and surplus material not intended for use within the lead specified above shall also, if necessary, be transported with all lifts and lead beyond initial 1000 m, disposed of or used as directed by the Engineer-in-charge.

 

Measurements for pavement

Excavation shall be measured by taking cross-sections at suitable intervals in the original position before the work starts and after its completion and computing the volumes in cu.m. by the method of average end areas for each class of material encountered. Where it is not feasible to compute volumes by this method because of erratic location of isolated deposits, the volumes shall be computed by other accepted methods.

            At the option of the Engineer-in-charge, the contractor shall leave depth indicators during excavations of such shape and size and in such positions as directed so as to indicate the original ground level as accurately as possible. The contractor shall see that these remain intact till the final measurements are taken.

            For rock excavations, the overburden shall be removed first so that necessary cross-sections could be taken for measurement. Where cross sectional measurements could not be taken due to irregular configuration or where the rock is admixed with other classes of materials, the volumes shall be computed on the basis of stacks of excavated rubble after making 35 percent deduction made will be to the extent of 16 percent of stacked volumes.

            Works involved in the preparation of cut formation shall be measured in units indicated below:

1

Loosening and recompacting the loosened material at subgrade

cu.m.

2

Loosening and removal of unsuitable material and replacing with a suitable material and compacting to required density

cu.m.

3

Preparing rocky subgrade

Sq.m.

4

Stripping including storing and reapplication of topsoil

cu.m.

5

Disposal of surplus material beyond initial 1000m lead

cu.m.

 

 

Rates

            The contract unit rates for the items of roadway excavation shall be payment in full for carrying out the operations required for the individual items including full compensation for:

(i)     Setting out

(ii)   Transporting the excavated materials and depositing the same on sites of embankment, spoil banks or stacking as directed within all lifts and lead upto 1000m or as otherwise specified

(iii) Trimming bottoms and slopes of excavation

(iv) Dewatering

(v)   Keeping the work free of water

(vi) All labour, materials, tools, equipment, safety measures, testing and incidentals necessary to complete the work to specifications

The contract unit rate for loosening and recompacting the loosened materials at subgrade shall include full compensation for loosening to the specified depth, including breaking clods, spreading in layers, watering where necessary and compacting to the requirements. The contract unit rate for item of preparing rocky sub grade shall be full compensation for providing, laying and compacting granular base material for correcting surface irregularities including all materials, labour and incidentals necessary to complete the work and all leads and lifts. The contract unit rate for items stripping and storing topsoil and of application of topsoil and of reapplication of topsoil shall include full compensation for all the necessary operations including all lifts, but leads up to 1000m. The contract unit rate for disposal of surplus earth from roadway and drain excavation shall be full compensation for all labour, equipment, tools, and incidentals necessary on account of the additional haul or transportation involved beyond the initial lead 1000m.

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